Aquatic and Land Animal Diversity

Fish

How many fish species inhabit the Earth—from freshwater to oceans?

According to recent estimates, more than 28,000 fish species inhabit freshwater and ocean waters. They are divided into thirty-six orders and 400 families in one of the more common classification systems. The majority of fish species are bony fish (class Osteichthyes, often called true fish), with skeletons made mostly or only of bones; others have skeletons of cartilage (class Chondrichthyes).